Published German patent document DE 198 26, 047 describes a device for controlling a gas-exchange valve of an internal combustion engine and the corresponding operating method. A high-pressure pump pumps hydraulic fluid into a piping system in which the hydraulic fluid is stored under very high pressure. A working chamber of an hydraulic cylinder whose piston is connected to a valve element of a gas-exchange valve of an internal combustion engine is connected to the fluid reservoir via a two-way valve. An outlet of the working chamber is also connected to a low-pressure region via a two-way valve. Depending on the valve setting, high or low pressure prevails in the working chamber of the hydraulic actuator and a corresponding fluid volume is present in the working chamber, which affects the piston position.
The advantage of such a gas-exchange valve is that it may be triggered independently of a setting of a camshaft of the internal combustion engine. For cost reasons, no detection of the instantaneous piston position takes place. As a result, the positioning of the piston of the hydraulic actuator is not able to be precisely regulated.
An object of the present invention is to provide a method such that the actuating element of the actuator is able to be positioned as precisely as possible.